Tim-4 Inhibits NO Generation by Murine Macrophages.

ABSTRACT:

Objective

T cell immunoglobulin- and mucin-domain-containing molecule-4 (Tim-4) receives much attention as a potentially negative regulator of immune responses. However, its modulation on macrophages has not been fully elucidated so far. This study aimed to identify the role of Tim-4 in nitric oxide (NO) modulation.

Methods

Macrophages were stimulated with 100 ng/ml LPS or 100 U/ml IFN-?. RT-PCR was performed to detect TIM-4 mRNA expression. Tim-4 blocking antibody and NF-?B inhibitory ligand were involved in the study. NO levels were assayed by Griess reaction. Phosphorylation of NF-?B, Jak2 or Stat1 was verified by western blot.

Results

Tim-4 was up-regulated in murine macrophages after interferon-gamma (IFN-?) stimulation. Tim-4 over-expression decreased NO production and inducible nitric oxide synthase (iNOS) expression in lipopolysaccharide (LPS) or IFN-?-stimulated macrophages. Consistently, Tim-4 blockade promoted LPS or IFN-?-induced NO secretion and iNOS expression. Tim-4 over-expression decreased LPS-induced nuclear factor kappa B (NF-?B) p65 phosphorylation in macrophages, which was abrogated by NF-?B inhibitory ligand. On the contrary, Tim-4 blocking increased LPS-induced NF-?B signaling, which was also abrogated by NF-?B inhibition. In addition, Tim-4 blockade promoted Jak2 and Stat1 phosphorylation in IFN-? stimulated macrophages.

Conclusion

These results indicate that Tim-4 is involved in negative regulation of NO production in macrophages, suggesting the critical role of Tim-4 in immune related diseases.

SUBMITTER: Xu LY 

PROVIDER: S-EPMC4408120 | biostudies-literature | 2015

REPOSITORIES: biostudies-literature